In the prior art, spectroscopic multi-channel measurements are based on imaging spectrometers. For example, shortwave near infrared measurements which may be done in conjunction with manufacturing process of paper or corrugated cardboard and which are made for providing information about moisture and/or other properties, may utilize imaging spectroscopy. However, the imaging spectroscopic measurement set-up is structurally and technically complicated. Additionally, cameras for the imaging spectroscopy are non-linear in response, their commercial availability is poor and potentially available ones are expensive. Furthermore, all measurement channels have common parameters such as amplification and dynamic range irrespective of the qualities or levels of the signals in the measurement channels.
Hence, there is a need to improve the optical multi-channel measurements.